A block diagram showing feedback control using three sensory modalities, namely, (1) thumbpad sensation, (2) non-digital mechanoreceptors and, (3) vision. The mathematical model is a specific implementation of this block diagram that uses simple proportional feedback control and the entire closed-loop dynamics of this system is modeled as a subcritical pitchfork bifurcation. Time-delays (Δt) and noise (σ) are explicitly labeled only for the sensory branches since for the purpose of this study, only the sensory time-delays and noise affect the relative usefulness of various modalities.